<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .container {
            width: 1000px;
            border: 1px solid blue;
            margin: 0 auto;
        }
        .header .logo {
            background-color: #2e6da4;
            width: 200px;
            float: left;
        }
        .header .search {
            background-color: rgba(0,0,0,0.5);
            width: 600px;
            float: left;
        }
        .header .txt {
            background-color: red;
            width: 200px;
            float: left;
        }
        .nav {
            text-align: center;
        }
        .section {

        }
        .section .left {
            background-color: #2b542c;
            width: 490px;
            float: left;
        }
        .section .right {
            background-color: #3c763d;
            width: 500px;
            float: right;
        }
        .footer {
            background-color: black;
        }
        .clear {
            clear:both ;
        }
    </style>

</head>
<body>
<div class="container">
    <div class="header">
        <div class="logo">1</div>
        <div class="search">aaaa</div>
        <div class="txt">你好，欢迎</div>
    </div>
    <div class="nav">导航</div>
    <div class="section">
        <div class="left">aa<br>aa<br>aa<br>aa<br>aa<br>aa<br>aa<br>aa<br>aa<br>aa<br>aa</div>
        <div class="right">bb<br>bb<br>bb<br>bb<br>bb<br>bb<br>bb<br></div>
        <div class="clear"></div>
    </div>

    <div class="footer">44444</div>

</div>
</body>
</html>